Catalyst for preparation of unsaturated aldehydes and acids

ABSTRACT

Unsaturated aldehydes and acids as acrolein and acrylic acid or methacrolein and methacrylic acid are prepared in excellent yields and at improved rates by the oxidation of propylene or isobutylene in the presence of a versatile catalyst containing molybdenum oxide, tellurium oxide and a boron phosphate. Calcination of the boron phosphate alone or in the catalyst mixture about 450* C. favors formation of aldehydes.

United States Patent Eden 1451 V Dec. 19,1972

[54] CATALYST FOR PREPARATION OF UNSATURATED ALDEHYDES AND ACIDS [72] Inventor: Jamal S. Eden, Akron, Ohio [73] Assignee: The B.F. Goodrich Company, New

York, N.Y.

[22] Filed: April 5, 1971 [2]] Appl. No.: 131,501

Related U.S. Application Data [62] Division of Ser. No. 838,349, July 1, 1969, Pat. No.

[52] U.S. Cl. ..252/432, 262/533 N, 260/604 R [51] Int. Cl. ..B01j 1 1/82 [58] Field of Search ..260/533 N, 604 R; 252/432 [56] 7 References Cited UNITED STATES PATENTS 3,255,238 Roelen et al ..252/432 X Unger ..252/432 X Eden ..252/437 Primary Examiner-Patrick P. Garvin AttorneyJ. Hughes Powell, Jr.

[57] ABSTRACT 3 Claims, No Drawings CATALYST FOR PREPARATION OF UNSATURATED ALDEIIYDES AND ACIDS This is a division of application Ser. No. 838,349, filed July 1, l969 and now US. Pat. No. 3,634,502.

BACKGROUND OF THE INVENTION Processes for preparing mixtures of unsaturated aldehydes and unsaturated carboxylic acids by oxidation of olefins at elevated temperatures over a catalyst are know. Catalysts for such processes contain for example, molybdenum oxide, tellurium oxide and heavy metal phosphates, as well as-catalysts containing certain heavy metal molybdates, tellurium oxide and phosphorus oxide. It is desirable to have processes for the preparation of the unsaturated aldehydes and acids wherein the ratio of aldehyde to acid obtained may be varied. While with some catalysts this may be done to some extent by varying reaction conditions, it is desirable to have other methods.

SUMMARY OF THE INVENTION When olefins such as propylene or isobutylene are reacted with oxygen at an elevated temperature in the presence of a novel catalyst initially containing molybdenum oxide, tellurium oxide and boron phosphate, excellent conversion and yield of propylene to acrolein and acrylic acid are obtained. It has also been found, quite unexpectedly, that if there is used in the process a catalyst wherein the borophosphate, alone or in the catalyst mixture, is calcined at a temperature above 450 C., formation of aldehyde is favored.

DETAILED DESCRIPTION The reactants for providing aldehydes and acids are propylene or isobutylene, a molecular oxygen-contain- The particle size of the catalyst for fixed bed operations may be from about to 18 mesh. Larger and smaller size particles may be used in fixed beds if desired. For fluid bed operations, catalyst size normally will range from about 80 to 325 mesh (U.S. Sieve).

The active catalyst containing molybdenum oxide, tellurium oxide and the boron phosphate may be prepared by a number of methods and may be supported or unsupported. The catalyst ingredients may be mixed in the form of solutions or slurries, or can be dry blended. Supportedcatalysts may be prepared by adding a dry support or aqueous slurry thereof to the catalyst ingredients. Among suitable supports are silica, silica-containing alumina, titania, zirconia, materials such as diatomaceous earth, kieselguhr, pumice, silicon carbide, clay, alumina, aluminum phosphate and the like.-

The catalyst used in accordance with the improved process of this invention may be prepared from solutions or slurries of the necessary ingredients or precursors thereof. The variable relating to ratios of aldehyde ing gas which can be pure oxygen, oxygen diluted with i an inert gas, oxygen enriched air or air per se.

Stoichiometric ratios of oxygen to olefin for the purposes of this invention are 1.5 :1. While lower ratios of oxygen can be used at a sacrifice of yield, it is preferred to use an excess of oxygen. Large excessesof oxygen while not undesirable, introduce process problems particularly if air is the source of the oxygen. An amount of oxygen from about 2 to about 6 mols of oxygen per mol of olefin is an adequate range.

The use of steam in the reaction while desirable is not absolutely essential. The amount of steam used may be varied from about 0 to 10 or more mols per mol of olefin. Other diluent gases such as nitrogen, saturated hydrocarbons such as propane may be used.

The reaction may be carried out in either fixed or fluidized catalyst bed.

The reaction temperature can range from about 300 C. to about 550 C. A preferred range is from about 350 C. to about 450C.

The contact time may vary considerably in the range of greater than 0.1 seconds. Good results have been obtained within the range of about 6 to about 60 seconds. While advantage may be taken of the short contact time, longer times may be used if desired.

The reaction may be conducted at atmospheric pressure, in a partial vacuum, or under induced pressures up to 100 psi or higher. Atmospheric pressure is preferred for fixed bed systems and higher pressures for fluid bed reactions.

and acid obtained is in part relatable to the treatment given to the boron phosphate, either alone or in admixture with the other necessary catalyst ingredients. When the boron phosphate is calcined at temperatures of about 450 C., or below, either alone, or in admixture with the other catalyst ingredients and the mixture calcined at temperatures below about 450 C., substantial proportions of acrylic acid in relation to acrolein may be obtained under proper reaction conditions. However, and this is quite unexpected, it was found that when the boron phosphate is calcined above 450 C., preferably above 475 C., either before admixture with the other catalyst ingredients, or the mixture of catalyst ingredients including the boron phosphate is calcined above 450 C., as about 500 C., under equivalent reaction conditions a very high ratio of unsaturated aldehyde to unsaturated acid is obtained. Thus, under process conditions where aldehyde is desired without extreme variation in operating conditions, one may obtain high yields of acrolein and smaller yields of acrylic acid with catalysts so prepared; and conversely, when increased yields of acrylic acid are desired, catalysts prepared with the v boron phosphate calcined at temperatures below about 450 C. may be employed. 'Thus, a versatile catalyst and process is provided in accordance with this invention whereby ratios of unsaturated aldehydes and acids are suitably varied by calcination at varying temperatures, as between about 400-550 C. Calcination for 8-16 hours is satisfactory. 7

The molar ratio of catalyst constituents is about 1-10 mols of molybdenum oxide, 1-10 mols of tellurium oxide and 1-10 mols of boron phosphate. Good results are obtained, for example, with ratios of about M00 15 to 50 TeO, and 25 to 100 BPO,.

EXAMPLES Runs were made in a fixed bed reactor of a high silica (Vycor) glass tube 12 inches long and 30 mm outer diameter. The reactor had inlets for air, steam and propylene. External electrically operated heating coils were wound on the reactor. OUtlet vapors were passed through a water cooled condenser and the uncondensed gases were passed through a gas chromatograph and analyzed continuously. The liquid condensate was weighed and analyzed for unsaturated acid and aldehyde in the gas chromatograph.

A catalyst was prepared by first preparing the boron phosphate. 123 grams (2 mols) of boric acid dissolved were separately fed intothe reactor from preheaters at a temperature of about 200 to 250, C. Before the propylene .was added, the reactor was preheated to about 285 C. The molar ratio of reactants used, mols in warm water at 60 C. was mixed with 231 grams (2 of oxygen and water per mol of olefin, oxygen (as air), mols) of 85% H,PO The resulting mixture was the reaction temperature, contact time (calculated at evaporated to dryness on a steam bath and calcined in a room temperature and pressure), conversion and yield hottube oven for 16 hours at 400 C. 203.29 grams in the several runs are set forth in the table in runs 1-7.

I DATA TABLE Mo! 3153?? Contact percent propylene conv. Temp. time, Oxygen, Water, propylene Run 0.) seconds mols mols conv. Acrolein A. acid 1... 3:41 23. 5 3. 04 3. 75 85. n as. 66 6.81 2 375 28. 5 3. ()2 5. 3 86. 2 87. 74 6. 41 3. 3113 2a. 3 3. 02 a. 3 114. s 13. 3a 14. 35 4. 400 2a. 5 3. 02 5. 3 34. 3 13. 4s 15. 5 3115 23. 0 4. 02 s. as 97. 5 76. so 14. 01 s. 385 111.0 5.0 5.3 88.8 as. 43 1). 22 I 7. 413 m. 0 s. o 5. 3 112.7 75. 66 14. 39 s. 40.1 411. 0 4. 02 3. 36 100 35. 06 42. 57 9... 400 41;. 0 4. 02 3. 96 100 49. 82 31. so

(1.2 mols M00 of molybdic acid slurried in water at a When e catalyst described in Example I was concentration of 85 percent was added to 84.64 grams pr p r i the Same manne again with the difference (0.8 mol) of the calcined BPo. slurried in water, and that the catalyst was calcined no higher than 0 C-. 63.84 grams (0.4 mol) of TeO slurried in water was increased yields of acrylic acid are noted at temperaadded to this mixture. The mixture formed was then lures in the range of about as demonstrated in evaporated to dryness on a steam bath and calcined in a Runs 8 and 9 in the data tablehot tube oven for 16 hours at 400 C., 16 hours at 450 lclaim! C., and for 5 hours at 500 C. The resulting catalyst A iatalyst consisting essentially f molybdenum contained a molar ratio of 75 l bd id 25 oxide, tellurium oxide and boron phosphate in a molar tellurium oxide and 50 boron phosphate. The catalyst was ground to 10-18 mesh, 80 l, f catalyst was 2. Acatalyst of claim 1 wherein the molar ratio is placed in the reactor. 1:0.1-1 :O.l2.

Steam at a temperature of 200 to 250 C. was first A Catalyst of claim 2 on a ca uppo fed into the reactor, and thereafter propylene and air UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,706,692 Dated December 19, 1972 InventorQiX Jamal S. Eden It is oertified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 6M, "OUtlet" should read -Outlet---.

Column 4, line 33, Claim 2, "l:O.l-l:0.l2" should read ---l:O.l-l:O'.l-2

Signed and sealed this 9th day of April 197M.

(SEAL) Atte st:

EDWARD M.FLITCHER,JR. C. MARSHALL DANE Attesting Officer Commissioner of Patents USCOMM-DC 6037 6-P69 UIS GOVERNMENT PRINTING OFFICE: I91! 0-356-331 

2. A catalyst of claim 1 wherein the molar ratio is 1:0.1-1:0.1-2.
 3. A catalyst of claim 2 on a silica support. 